PHILADELPHIA (CBS) – This month the Benjamin Franklin Bridge celebrates its 85th birthday. It’s just one of many projects that architect Paul Philippe Cret designed.

Although he was born in France, Cret settled in Philadelphia, and the firm that he started continues today as H2L2. It is now the oldest architectural firm in the country.

“We’re sitting in the Cret Library at our office,” said senior partner Barry Eiswerth during a recent tour, “and this was designed in 1926, about the same time as the bridge. It’s art deco. These pieces of furniture here were mockups for the furniture at the Federal Reserve Board.”

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(The Cret Library at H2L2 is decorated with Cret's portrait and graphics of some of his landmark accomplishments. Photo by Lauren Lipton)

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Originally, the bridge was battleship grey. When it was time to repaint it in 1976, the Cret firm was brought in to decide on a new color. Eiswerth says they came up with a couple of alternatives.

“A really beautiful blue that looks good in a grey sky, in a bright sky, and at night as the sun is setting. The other choice was an eggplant color.”

As everyone knows, the Delaware River Port Authority went with the blue.

(Barry Eiswerth. File photo provided)

And, Eiswerth (right) says, someday soon you may see part of the bridge that hasn’t been seen in many decades.

“There were four wonderful, gilded angels at the entry points, and they are currently in storage underneath the Franklin Square monument. There’s talk of bringing them back,” he adds.

One of the most amazing trivia facts about the Ben Franklin Bridge is that when the bridge opened, there were no posted speed limits. Drivers were expected to just use their common sense. Imagine that.